The present invention relates generally to straightening and testing devices, and more particularly to an arrow straightener and testing apparatus adapted to straighten bent metallic shafts of arrows and to test the spine strength of wooden arrow shafts.
Arrow shafts used in archery can be fabricated of a variety of materials such as wood, metal, fiberglass and graphite. Metallic arrow shafts, usually either stainless steel or aluminum, often bend when they strike and ricohet off a solid object, such as a rock, target butt or wood.
Rather than disposing of bent arrows, it is often desirable to straighten them so they can be used again. Although it is possible to straighten the arrows by hand, such manual straightening usually lacks the necessary precision to obtain a shaft sufficiently straight for accuracy and desirable performance in archery shooting.
There are several devices available to assist in straightening arrow shafts and which are effective to varying extents. For example, U.S. Pat. No. 2,876,822, issued to H. Groves discloses an arrow runout tester and straightener apparatus having two spaced-apart arrow supports, press means for applying straightening pressure to the arrow, and indicator means to measure and indicate the deflection of the arrow. U.S. Pat. No. 3,846,998, issued to W. Lock discloses another variation in arrow straightener apparatus which includes two adjustably spaced-apart supports, press means for applying a straightening force, and a deflection gauge positioned alongside the press means. Each support of the lock device also includes a pair of axially rotatable bearings mounted in tandem relation to each other upon which the arrow shaft is supported and belt drive means for rotating the bearing supports about their respective axes to impart rotating motion to the arrow shafts. While these devices are effective in straightening arrows, it is not uncommon for such devices to cause crimps, dents or kinks in the arrow shaft at the point of support, particularly in situations in which the arrow is severely bent so tha it does not lay flat on the support bearing surfaces, and their deflection indicators may not be as accurate as would be desirable.
It is also customary to grade and classify wooden arrow shafts according to spine strength as indicated by a standard deflection measurement resulting from suspending a two-pound weight from the arrow shaft midway between two supports spaced 26 inches apart from each other. Therefore, it is desirable for a complete arrow service apparatus to include spine strength testing capabilities as well as straightening capabilities.